It is known that the benzazepine compounds of the above formula (1) or salts thereof are useful as an intermediate for preparing a pharmaceutically active benzazepine compound having vasopressin antagonistic activity, e.g. the compounds (10) as mentioned hereinafter (cf. JP-A-4-154765).
It is also known that the benzazepine compounds (1) have been prepared by the processes as shown in the following Reaction schemes A and B (cf. JP-A-4-154765 and Kazumi Kondo et al., Bioorganic & Medicinal Chemistry 7 (1999), pp. 1743-1754).
wherein R1, R2 and X1 are as defined above.
wherein R1, R2 and X1 are as defined above.
However, the methods shown in the above Reaction Schemes A and B are not suitable for producing the desired compounds (1) on industrial scale. That is, the starting compound (4) to be used in Reaction Scheme A is hardly obtainable in high yield and in high purity, and hence, the method of Reaction Scheme A is not suitable as an industrial process. Besides, the method of Reaction Scheme B can not give the desired compounds (1) in high yield and in high purity, and hence it is not suitable as an industrial process.
It is further known that the benzoic acid compounds of the above formula (4) are useful as an intermediate for preparing a pharmaceutically active benzazepine compound having vasopressin antagonistic activity (cf. JP-A-4-154765). The benzoic acid compounds (4) are usually prepared by a process as shown in the following Reaction Scheme C (cf. Yasuhiro Torisawa et al., Bioorganic & Medicinal Chemistry Letters, 10 (2000), pp. 2493-2495).
